Estimation of MUF(3000)F2 using Earth-ionosphere geometry for Karachi and Multan, Pakistan

Abstract

• Earth-ionosphere geometry is used for MUF estimation with h’F2 replacing hmF2. • Linear regression analysis reduces error in MUF estimation to 2 MHz. • The methodology may be applicable for HF communication support. We report the estimation of the Maximum Usable Frequency of F2-layer for 3000 km circuit ( MUF ( 3000 ) F 2 ) using Earth-ionosphere geometry. The study is based on the assumption that h ′ F 2 may replace hmF 2 to estimate M ( 3000 ) F 2 . The monthly hourly medians of f o F 2 , h ′ F 2 , and M ( 3000 ) F 2 are extracted for Karachi (geog. coord. 24.9 ° N, 67.3 ° E) & Multan (30.2 ° N, 71.5 ° E) during 1996, 1992, & 1989 representing low, moderate & high solar activity years, respectively. The MUF ( 3000 ) F 2 estimated using spherical geometry shows large deviation and greater Root Mean Square Error values (RMSE > 4 MHz) on comparison with MUF ( 3000 ) F 2 observed from ionosonde. In order to reduce the error, linear regression analysis technique is used and applied on independent data set of years 1995, 1993 and 1991 representing low, moderate and high solar activity to compute corrected MUF ( 3000 ) F 2 , respectively. It is found that corrected MUF is in good agreement with observed MUF decreasing RMSE to less than 2.0 MHz for the stations and years under study. The results of this study would be helpful in MUF estimation using h ′ F 2 and also in improving radio services for smooth HF communication.